FYI, libstdc++-v3 ./configure bootstrap problem "permanently" fixed

[Loren James Rittle]

I just installed the top-level patch to "permanently" fix a source of
annoying PRs...

Phil, it isn't exactly the technique you had lobbied for over the
years, but it is the same effect for us at least.  "srcdir!=objdir"
within libstdc++-v3 is now always valid to assume.  (Maybe wait 24
hours to make sure we don't get unrolled then:) Feel free to begin
removing any library Makefile complexity which assumed otherwise.

Regards,
Loren